linux-kernel - Re: [PATCHv2 2/2] spi: orion: Add multiple chip select support to spi-orion

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Message-ID: <20150114200626.GN3043@sirena.org.uk>
Date:	Wed, 14 Jan 2015 20:06:26 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Ken Wilson <ken.wilson@...ngear.com>
Cc:	thomas.petazzoni@...e-electrons.com, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	ezequiel.garcia@...e-electrons.com, gerg@...inux.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-spi@...r.kernel.org
Subject: Re: [PATCHv2 2/2] spi: orion: Add multiple chip select support to
 spi-orion

On Mon, Jan 12, 2015 at 01:14:00PM +1000, Ken Wilson wrote:

> +- num-cs     : The total number of chip selects used by this platform.
> +		If unset, this defaults to 1.

So, this is intended to be the number of hardware chip selects that can
be configured but the first commit mentioned GPIOs as an option too so
we should at least say that this is specifically the controller
supported ones.  However...

> +#define ORION_SPI_CS_MASK	0x1C
> +#define ORION_SPI_CS_SHIFT	2
> +#define ORION_SPI_CS(cs)	((cs << ORION_SPI_CS_SHIFT) & \
> +					ORION_SPI_CS_MASK)

...given that we have a fixed bitfield here which we know and doesn't
appear to depend on configuration do we even need this to be
configurable - given that we're going to need an explicit node for any
slave can't we just accept any sane chip select for a slave without
extending the binding?

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